Step by step video of how to clean historic gravestones. Uses D/2 Biological Solution, which is used by National Park Service to clean veteran's gravestones and monuments. http://www.gravestonecleaner.com/how-to-use-d2-biological-solution-to-clean-a-gravestone/
Billion Graves - Our goal is to preserve precious records found in cemeteries throughout the world. We use modern technology to capture images of headstones with their GPS locations so users worldwide can access those records anywhere. BillionGraves strives to do just that: preserve at least one billion graves.